DE 10 2004 009 130 A1 describes a gas inlet system for a MOCVD reactor wherein the process gases are fed into the process chamber at different heights through three gas inlet zones arranged vertically one above the other. The process chamber extends annularly around the gas inlet element, which is disposed in the center of symmetry of the gas chamber. For depositing a III-V semiconductor layer on a substrate, in each case the V component in the form of a hydride is fed through the lowermost and through the topmost gas inlet zone. Through the middle gas inlet zone lying therebetween, the III component in the form of an organometallic compound is fed into the process chamber. The three gas inlet zones arranged one above the other form gas inlet chambers, which are open toward the process chamber. Only the middle gas inlet chamber is closed off by an annular body made of a porous material. Said annular body is intended to act as pressure barrier. The substrates are annularly grouped around the gas inlet element disposed in the center of the process chamber.
DE 10 2005 056 320 A1 describes a CVD reactor having a gas inlet element which forms two gas inlet zones arranged vertically one above the other. A cooled lower end of the gas inlet element lies in a bottom cut-out of the susceptor, which is heated from below.
DE 101 53 463 A1 also describes a MOCVD reactor for depositing II-V semiconductor layers, the reactor having a gas inlet element disposed in the center of a process chamber. Here, the V component is fed into the process chamber through a front end opening on the lower side of the gas inlet element. The III component flows from a gas inlet chamber, disposed thereabove and enclosed by a porous ring, into the process chamber.